This application is based upon and claims priority to German Patent Application 100 19 309.9 filed Apr. 19, 2000, which application is herein expressly incorporated by reference.
The present invention relates to a method and device for rotary casting. Methods and devices are known from EP 0656819 and U.S. Pat. No. 5,626,180, where a mold with a downwardly opening ingate is moved together with a casting container with an upwardly opening aperture. Melt for one casting operation is filled into the casting container. The mold, together with the casting container, is rotated approximately 180xc2x0 around a horizontal axis so that the melt reaches the mold. In this case, the casting container is filled, via a filling aperture, which is provided with a special closure.
It is an object of the present invention to provide a method and device which improves productivity when using the method for mass production purposes. In a method of rotary casting, a mold with an upwardly pointing ingate end is mounted on a base plate. The finished mold is rotated with the base plate approximately 180xc2x0 around a horizontal rotational axis. Thus, the ingate end points downwardly. A casting container with an upwardly positioned aperture end is filled with melt for one casting operation. The casting container, by means of its aperture end, is sealingly coupled to the downwardly pointing ingate end of the mold. The mold, with the contacting casting container, is rotated by approximately 180xc2x0 around a horizontal axis so that the melt reaches the mold. The casting container is released from the coupled position and removed from the mold.
A device for rotary casting has a mold mounted on a base plate. An ingate points away from the upper face of the base plate. A bearing mechanism supports the base plate so that the base plate is rotatable around a horizontal rotational axis by at least 180xc2x0. A casting container has an aperture which may be positioned to point towards the upper face of the base plate. Also, moving means is coupled with the casting container to move the casting container with its aperture into a sealing arrangement with the downwardly pointing ingate of the mold. The casting container is rotatable together with the mold around a horizontal rotational axis by at least 180xc2x0. In the rotated position, the casting container may be removed from the upwardly pointing ingate of the mold.
In accordance with the inventive method and the inventive device, the mold, either manually or partly in an automated way, can be assembled easily and quickly. Assembling the mold is simplified and easily controllable. Furthermore, because the casting container is filled away from the mold, improved control exists when filling the casting container which does not require a special closure mechanism. Advantages of rotary casting are achieved by rotating the mold after it has been assembled and by coupling the casting container from below, e.g. by coupling the aperture of the casting container to the ingate of the mold. Accordingly, the casting operation is calm and turbulence-free when subsequently rotating back or further rotating the mold with the coupled casting container around a horizontal axis. In order to accelerate the process further and to prepare for the next casting operation, the casting container can be removed upwardly from the mold whose ingate now points upwards. Further, it becomes possible to place a pressure hood onto the upwardly opening ingate to improve the solidification process by applying gas pressure. Optionally, feeders positioned at the top end and coupled with the mold may be provided. The gas pressure is preferably applied after a complete, hardened surface layer has formed in the mold.
In principle, the mold may include molded material parts with a base plate of molded material. The mold may include a so-called core package where all the surfaces of the mold cavity are formed of cores. The mold can also be erected on a base plate made of metal. Optionally, the mold may contain side walls made of metal which receive inserted inner cores of molded material. The mold is upwardly sealed by a cover core made of molded material. This means the mold can form a so-called semi-die. Finally, the mold can be provided entirely in the form of a permanent mold. Here, the mold has a metallic base plate, metallic side walls and a metallic cover into which the required molded material cores are inserted. This means the mold can be provided in the form of a die.
In a preferred embodiment, the finish-assembled mold without the coupled-on casting container is rotated around the same horizontal axis as the mold with the coupled-on casting container. It is advantageous that the mold on its own and the mold together with the coupled-on casting container, in each case, be rotated around an axis which passes through the mold and is positioned near the base plate. This ensures that the entire assembly is supported approximately in the center of gravity. Preferably the rotational axis of rotation extends in the direction of the greatest extension of the inner cavity of the mold.
The method is preferably carried out in such a way that, for the purpose of coupling and removing the casting container to and from the mold, the casting container carries out a radial movement relative to the horizontal rotational axis. In order to transfer the casting container into a filling position, the casting container carries a pivoting movement around the axis of the radial movement. Accordingly, the necessary separation of the casting container from the mold can be achieved by simple movement sequences. Thus, the operations of assembling the mold and filling the casting container can overlap in terms of time.
The inventive device comprises a bogie with two cheek parts. Swivel pins are supported in the cheek parts. Furthermore, in a preferred embodiment, the casting container is displaceable on a column which is arranged radially relative to the horizontal swivel pins. The column is slid onto one of the swivel pins. In order to place the pivot movement into effect, the column is preferably provided with an attached radial pivot arm. The radial pivot arm is rotatable around the axis of the column. Also, the casting container is secured directly to the radial pivot arm.
Furthermore, it is proposed that, at its ingate end, the mold includes at least one ingate aperture and one gas discharge line. Both the ingate aperture and gas discharge line assume different angular positions relative to the horizontal rotational axis. In addition, the casting container may include an intermediate wall which, in a position where the casting container is coupled to the mold, extends parallel to the horizontal rotational axis. The intermediate wall dips into the melt and ends at a distance from the base of the casting container. The intermediate wall succeeds in holding back and wiping off oxide layers when the melt is fed into the casting container on one side of the intermediate wall and when rotating the casting container around 180xc2x0 towards the side. The casting container coupled to the mold is able to cover, via its aperture, both the ingate and the ventilation aperture of the mold. These two openings are positioned on different sides of the intermediate wall.
Preferably, the inventive device is used in a foundry plant such that at least two inventive devices are associated with a melting furnace with a dispensing ladle. The inventive devices are each movable to and fro in a linear movement between a casting station at the melting furnace and at least one solidification station. The assembly and removal of the mold preferably takes place in the casting station where all the handling elements are combined. However, it is also possible to provide a separate station to assemble and remove the mold. If the casting system includes two devices, it is referred to as a tandem system. If there are three devices, it is referred to as a tridem system. The tridem system constitutes the acceptable maximum.
According to a further embodiment, a plurality of inventive devices can be included in a foundry plant such that they are associated with a melting furnace with a dispensing ladle and that they are transferred on a circular track from one casting station to at least one solidification station. This is referred to as a carousel casting system. In this case, the casting station can form the mold assembly and mold removal station. However, in the case of the carousel casting system, it is advisable to provide a mold assembly and mold removal station which is separate from the solidification station.
In an embodiment which deviates from the foundry plant mentioned above, a melting furnace with an associated dispensing ladle can be combined with two inventive devices so that the devices are firmly assembled in a linear arrangement and the dispensing ladle can be moved to and fro between the devices and the melting furnace. In this way, it is possible to simplify the transport and handling facilities.
The above-mentioned latter foundry system can be varied. Here, a melting furnace with an associated dispensing ladle can be combined with a plurality of inventive devices. The devices are arranged in a circular formation such that the dispensing ladle can be pivoted to and fro between the melting furnace and the devices. For a larger number of devices, this is more advantageous then a linear arrangement.
From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.